The epoxy nanocomposites were named R-v-y, where x represents the added organoclay (that is bentonite, or APUA/ BFTDA functionalized bentonite) and y represents the overall amount of nanofiller in the sample (3 or 5%wt).
BFTDA was obtained via a low-cost one-pot 2 + 3 cycloaddition of dicyandiamide on nitrile groups (Scheme 1) with simple purification steps and high yield (90%).
Once the organic modifiers were successfully obtained, two organophilic clays, based on acidified BFTDA and APUA and labelled Bento-BTFDA and Bento-APUA respectively, were synthesized with an ion exchange process starling from pristine bentonite.
Furthermore, it is worth noting that all the organoclays containing samples display an inorganic clay solid residue at the end of the TGA run, whose amount well compares with the weight fraction of nanofiller in the feed, taking into account also the degradation of the organic fractions due to APUA and BFTDA.
The addition of Bento-BFTDA nanofillers, both at 3 and 5 wt%, leads to a significant improvement of the flame retardant properties (pHRR, FPI and FIGRA) of the nanoeomposites if compared with plain R-Bento, but they are still worse than plain resin (NEAT): the N-rich BFTDA is not enough to compensate the negative influence that the clay imparts in terms of flame behavior.
Two new organoclays were prepared from the modification of bentonite with nitrogen-based organic compounds BFTDA and APUA and used for the preparation of epoxy resin nanocomposites.